mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-12 22:30:12 +00:00
216 lines
4.7 KiB
C
216 lines
4.7 KiB
C
/* Check if effective user id can access file
|
||
Copyright (C) 1990-2020 Free Software Foundation, Inc.
|
||
This file is part of the GNU C Library.
|
||
|
||
The GNU C Library is free software; you can redistribute it and/or
|
||
modify it under the terms of the GNU Lesser General Public
|
||
License as published by the Free Software Foundation; either
|
||
version 2.1 of the License, or (at your option) any later version.
|
||
|
||
The GNU C Library is distributed in the hope that it will be useful,
|
||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
Lesser General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Lesser General Public
|
||
License along with the GNU C Library; if not, see
|
||
<https://www.gnu.org/licenses/>. */
|
||
|
||
/* Written by David MacKenzie and Torbjorn Granlund.
|
||
Adapted for GNU C library by Roland McGrath. */
|
||
|
||
#ifdef HAVE_CONFIG_H
|
||
# include <config.h>
|
||
#endif
|
||
|
||
#include <sys/types.h>
|
||
#include <sys/stat.h>
|
||
|
||
#ifdef S_IEXEC
|
||
# ifndef S_IXUSR
|
||
# define S_IXUSR S_IEXEC
|
||
# endif
|
||
# ifndef S_IXGRP
|
||
# define S_IXGRP (S_IEXEC >> 3)
|
||
# endif
|
||
# ifndef S_IXOTH
|
||
# define S_IXOTH (S_IEXEC >> 6)
|
||
# endif
|
||
#endif /* S_IEXEC */
|
||
|
||
#if defined HAVE_UNISTD_H || defined _LIBC
|
||
# include <unistd.h>
|
||
#endif
|
||
|
||
#ifndef _POSIX_VERSION
|
||
uid_t getuid ();
|
||
gid_t getgid ();
|
||
uid_t geteuid ();
|
||
gid_t getegid ();
|
||
#endif /* not POSIX_VERSION */
|
||
|
||
#include <errno.h>
|
||
#ifndef errno
|
||
extern int errno;
|
||
#endif
|
||
#ifndef __set_errno
|
||
# define __set_errno(val) errno = (val)
|
||
#endif
|
||
|
||
#if defined EACCES && !defined EACCESS
|
||
# define EACCESS EACCES
|
||
#endif
|
||
|
||
#ifndef F_OK
|
||
# define F_OK 0
|
||
# define X_OK 1
|
||
# define W_OK 2
|
||
# define R_OK 4
|
||
#endif
|
||
|
||
#if !defined S_IROTH && defined R_OK
|
||
# define S_IROTH R_OK
|
||
#endif
|
||
#if !defined S_IWOTH && defined W_OK
|
||
# define S_IWOTH W_OK
|
||
#endif
|
||
#if !defined S_IXOTH && defined X_OK
|
||
# define S_IXOTH X_OK
|
||
#endif
|
||
|
||
|
||
#ifdef _LIBC
|
||
|
||
# define group_member __group_member
|
||
# define euidaccess __euidaccess
|
||
|
||
#else
|
||
|
||
/* The user's real user id. */
|
||
static uid_t uid;
|
||
|
||
/* The user's real group id. */
|
||
static gid_t gid;
|
||
|
||
/* The user's effective user id. */
|
||
static uid_t euid;
|
||
|
||
/* The user's effective group id. */
|
||
static gid_t egid;
|
||
|
||
/* Nonzero if UID, GID, EUID, and EGID have valid values. */
|
||
static int have_ids;
|
||
|
||
# ifdef HAVE_GETGROUPS
|
||
int group_member ();
|
||
# else
|
||
# define group_member(gid) 0
|
||
# endif
|
||
|
||
#endif
|
||
|
||
|
||
/* Return 0 if the user has permission of type MODE on file PATH;
|
||
otherwise, return -1 and set `errno' to EACCESS.
|
||
Like access, except that it uses the effective user and group
|
||
id's instead of the real ones, and it does not check for read-only
|
||
filesystem, text busy, etc. */
|
||
|
||
int
|
||
euidaccess (const char *path, int mode)
|
||
{
|
||
struct stat64 stats;
|
||
int granted;
|
||
|
||
#ifdef _LIBC
|
||
uid_t euid;
|
||
gid_t egid;
|
||
#else
|
||
if (have_ids == 0)
|
||
{
|
||
have_ids = 1;
|
||
uid = getuid ();
|
||
gid = getgid ();
|
||
euid = geteuid ();
|
||
egid = getegid ();
|
||
}
|
||
|
||
if (uid == euid && gid == egid)
|
||
/* If we are not set-uid or set-gid, access does the same. */
|
||
return access (path, mode);
|
||
#endif
|
||
|
||
if (stat64 (path, &stats))
|
||
return -1;
|
||
|
||
mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */
|
||
#if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH
|
||
?error Oops, portability assumptions incorrect.
|
||
#endif
|
||
|
||
if (mode == F_OK)
|
||
return 0; /* The file exists. */
|
||
|
||
#ifdef _LIBC
|
||
/* Now we need the IDs. */
|
||
euid = __geteuid ();
|
||
egid = __getegid ();
|
||
|
||
if (__getuid () == euid && __getgid () == egid)
|
||
/* If we are not set-uid or set-gid, access does the same. */
|
||
return __access (path, mode);
|
||
#endif
|
||
|
||
/* The super-user can read and write any file, and execute any file
|
||
that anyone can execute. */
|
||
if (euid == 0 && ((mode & X_OK) == 0
|
||
|| (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
|
||
return 0;
|
||
|
||
if (euid == stats.st_uid)
|
||
granted = (unsigned int) (stats.st_mode & (mode << 6)) >> 6;
|
||
else if (egid == stats.st_gid || group_member (stats.st_gid))
|
||
granted = (unsigned int) (stats.st_mode & (mode << 3)) >> 3;
|
||
else
|
||
granted = (stats.st_mode & mode);
|
||
/* XXX Add support for ACLs. */
|
||
if (granted == mode)
|
||
return 0;
|
||
__set_errno (EACCESS);
|
||
return -1;
|
||
}
|
||
#undef euidaccess
|
||
#undef eaccess
|
||
#ifdef weak_alias
|
||
weak_alias (__euidaccess, euidaccess)
|
||
weak_alias (__euidaccess, eaccess)
|
||
#endif
|
||
|
||
#ifdef TEST
|
||
# include <stdio.h>
|
||
# include <errno.h>
|
||
# include "error.h"
|
||
|
||
char *program_name;
|
||
|
||
int
|
||
main (int argc, char **argv)
|
||
{
|
||
char *file;
|
||
int mode;
|
||
int err;
|
||
|
||
program_name = argv[0];
|
||
if (argc < 3)
|
||
abort ();
|
||
file = argv[1];
|
||
mode = atoi (argv[2]);
|
||
|
||
err = euidaccess (file, mode);
|
||
printf ("%d\n", err);
|
||
if (err != 0)
|
||
error (0, errno, "%s", file);
|
||
exit (0);
|
||
}
|
||
#endif
|